Dev train models

Hi @chadhat @nmarounina

I added you to this MR so that you know what the status of the project is.

So far the most important fuctionalities have been implemented:

• prefiltering of the data based on newspaper and topic
• preprocessing as described in the previous paper
• training of MNB and BERT
• Logging of train params and
• Evaluation of train runs based on train log-files

Missing prefiltering based on the hate-speech score will be added as soon as the data is available.